I've got an early-2011 15" MBP. Just installed Mavericks this afternoon and gave it a few hours to settle down (download mail, index, etc.). It's SLOW. Taking quite some time for apps to launch. There's a 1-2 second delay when using Messages to chat. Word takes 5-10 seconds to start. Things were much faster yesterday! In addition, I just got the battery replaced on this machine. I was getting 7-8 hours during light usage. Now, with the display dimmed and only light apps runnings, I am getting an estimated 6 hours. Overall, fairly disappointed. Anyone else having these problems?